1. Chapter 11 Death: Meaning, Manner, Mechanism, Cause, and Time
All Rights Reserved South-Western / Cengage Learning © 2012, 2009

2. Chapter 11 Death: Meaning, Manner, Mechanism, Cause, and Time By the end of this chapter you will be able to:
Discuss the definition of death
Distinguish between five manners of death: natural, accidental, suicidal, homicidal, and undetermined
Distinguish between cause, manner, and mechanisms of death
Explain the development of rigor, algor, and livor mortis following death
Forensic Science: Fundamentals & Investigations, Chapter 11
All Rights Reserved South-Western / Cengage Learning © 2012, 2009

3. Chapter 11 Death: Meaning, Manner, Mechanism, Cause, and Time By the end of this chapter you will be able to:
Estimate the time of death
Use evidence on stomach contents to estimate time of death
Use evidence from the eye to estimate time of death
Use insect evidence to estimate time of death
Explain how environmental factors can affect the estimated time of death
Forensic Science: Fundamentals & Investigations, Chapter 11

4. Definition of Death Cessation, or end, of life
Irreversible cessation of blood circulation
Cessation of all brain activity
Experts do not agree on a single definition
Forensic Science: Fundamentals & Investigations, Chapter 11

5. The Manner of Death The manner of death can be
Natural, the most common
Accidental
Suicidal
Homicidal
Undetermined
List some examples of each.
Sometimes the manner of death is difficult to determine
Forensic Science: Fundamentals & Investigations, Chapter 11

6. Cause and Mechanism of Death
Cause of death is the reason for the death
List some causes of death.
Forensic Science: Fundamentals & Investigations, Chapter 11

7. Cause and Mechanism of Death
Mechanism of death is the specific change in the body that brought about the cessation of life
List some mechanisms of death.
Forensic Science: Fundamentals & Investigations, Chapter 11

8. Time of Death—Livor Mortis
The Leaden-Color of Death
Lividity—With decomposition, blood seeps down and settles in the lower parts of a body
Red blood cells turn bluish-purple
Forensic Science: Fundamentals & Investigations, Chapter 11

9. Time of Death—Livor Mortis
Lividity begins about two hours after death
Discoloration becomes permanent after eight hours
Ambient temperature affects the speed of decomposition
Lividity can determine the position of the body during the first eight hours
Caution: Next photos are REAL.
Forensic Science: Fundamentals & Investigations, Chapter 11

10. Time of Death—Livor Mortis
What might cause the uncolored region?
Forensic Science: Fundamentals & Investigations, Chapter 11

11. Time of Death—Livor Mortis
What does this livor mortis tell us?
Forensic Science: Fundamentals & Investigations, Chapter 11

12. Time of Death—Livor Mortis
What might cause the uncolored region? What does this tell us?
Forensic Science: Fundamentals & Investigations, Chapter 11

13. Time of Death—Rigor Mortis
The Rigidity of Death
Without oxygen in the blood—
Muscles stiffen
Starts in the head and expands throughout
After about 15 hours—
Muscle fibers begin to dissolve
Softening begins
CAUTION: Real photos ahead.
Forensic Science: Fundamentals & Investigations, Chapter 11

14. Time of Death—Rigor Mortis
The Rigidity of Death
Forensic Science: Fundamentals & Investigations, Chapter 11

15. Time of Death—Rigor Mortis
The Rigidity of Death
Unnatural position
indicates someone
moved the body
Forensic Science: Fundamentals & Investigations, Chapter 11

16. Time of Death—Rigor Mortis
Live muscle fibers slide back and forth
After death, muscle fibers become locked in a flexed position
Forensic Science: Fundamentals & Investigations, Chapter 11

17. Time of Death—Rigor Mortis
Observation
Approx. Time Scale
No visible signs of rigor
Less than 2 hours
or more than 36 hours ago
Body at peak of rigor
Around 12 hours
Stiffness generally disappears
After 36 hours
Forensic Science: Fundamentals & Investigations, Chapter 11

18. Time of Death—Rigor Mortis
Factors affecting rigor mortis:
Ambient temperature (heat rigor and softening)
Weight of the body (heavier rigor)
Type of clothing, or lack of it (warm clothing
rigor)
Forensic Science: Fundamentals & Investigations, Chapter 11

19. Time of Death—Rigor Mortis
Factors affecting rigor mortis:
General health of person at time of death
Level of physical activity at time of death
(exercise right before death rigor in the active muscles)
Sun exposure (heat )
Forensic Science: Fundamentals & Investigations, Chapter 11

20. Time of Death—Algor Mortis
The Chill of Death
Body heat falls after death
About 0.78°C per hour immediately after death
Slowing to less than 0.39°C per hour after about 12 hours
Heat loss is affected by the ambient temperature
Forensic Science: Fundamentals & Investigations, Chapter 11

21. Time of Death—Algor Mortis
The Chill of Death
Corpse temperature is measured by a thermometer inserted into the liver
Time of death is expressed as a range of time
Forensic Science: Fundamentals & Investigations, Chapter 11

22. Time of Death —Stomach and Intestinal Contents
State of Contents
Timing of Death
Undigested food present in the stomach
Zero to two hours after the last meal
Stomach is empty, but food found in small intestine
Death occurred at least four to six hours after a meal
Small intestine is empty; waste found in large intestine
Death occurred 12 or more hours after a meal
Forensic Science: Fundamentals & Investigations, Chapter 11

23. Time of Death —Stomach and Intestinal Contents
Forensic Science: Fundamentals & Investigations, Chapter 11

24. Time of Death —Stages of Decomposition
Choose: A. Within 2 days. B. After 4 days. C. Within 6-10 days.
Fluids begin to leak from body openings as cell membranes rupture
Discoloration of the face
The skin sloughs off
The skin blisters
Green and purplish staining from blood decomposition
The corpse bloats
Eyeballs and other tissues liquefy
The abdomen swells
Marbling appearance on the skin
Forensic Science: Fundamentals & Investigations, Chapter 11

25. Time of Death—Insects Forensic entomologist
Collects insect evidence from on, above, and below the body
Records environmental conditions
Within minutes of a death, certain insects arrive to lay their eggs on the warm body—blowflies
As the corpse decomposes, other kinds of insects arrive
Forensic Science: Fundamentals & Investigations, Chapter 11

26. Time of Death —Blowfly Life Cycle
<8 hours after death—blowfly eggs can be found in the moist, warm areas of a corpse
Within 20 hours—1st of their 3 larva stages
4th or 5th day—3rd of their 3 larva stages
Forensic Science: Fundamentals & Investigations, Chapter 11

27. Time of Death —Blowfly Life Cycle
8 to 12 days—larvae migrates to a dry place
18 to 24 days— Early pupa; immobile; changes from light brown to dark brown
By the 21st-24th day the pupa cases will split open and adult blowflies will emerge.
Forensic Science: Fundamentals & Investigations, Chapter 11

28. Time of Death—Insects
The insect life cycle provides scientists with a benchmark to estimate a time of death
Insect evidence cannot provide an exact time of death—fluctuating environmental conditions
Insect evidence provides a close estimate
Forensic Science: Fundamentals & Investigations, Chapter 11

29. . . . . . . . . . . . . . . . . . Summary Several definitions of death
A body decomposing through three stages— livor, rigor, and algor mortis—provides an estimated time of death
Stomach contents and insect evidence also aid in estimating the time of death
Environmental factors affect the estimated time of death
Forensic Science: Fundamentals & Investigations, Chapter 11